The present invention relates to an air data sensor probe that will sense angle of attack or angle of sideslip as well as pivot and static pressure, and which is designed to substantially reduce drag, deicing/anti-icing power and weight over normal strut mounted probes, but yet give reliable results. The probe has an aerodynamically formed housing that extends like a small bulge outwardly from the side skin of an aircraft with angle sensing ports and a pitot port on a leading end, and static pressure sensing ports positioned in desired locations aft of the pitot port entry.
In the prior art, angle of attack has generally been measured either by vane sensors, cone sensors or multifunction probes with angle sensitive pressure ports. Vane sensors swivel about an axis to indicate changes in relative airflow direction, with suitable circuits for indicating the angle change. Multi-function probes have a barrel with top and bottom ports at the leading end of the barrel, and as the probe barrel axis changes angle, the ports sense differential pressure, to give an indication of angle of attack.
Static pressure has been sensed on probe assemblies as well, and flush mounted plates that have static pressure sensing ports in them are also utilized.
It is desirable to reduce drag and weight on high performance aircrafts, but reliable indications of angle of attack and static pressure are required for satisfactory high performance aircraft operation that is safe.
The present invention relates to a multi-function air data sensor that comprises an aerodynamically shaped body or housing protruding slightly from a mounting plate that is placed onto and is flush with the skin of an aircraft. The aerodynamic shape includes a rounded (part spherical) forward end, and smoothly contoured surfaces downstream from the forward end to result in low drag as air flows past the semi-flush body. The body is elongated in fore and aft direction generally aligned with the airflow. A cross section taken along a plane substantially perpendicular to the fore and aft axis and to the mounting area of the skin of the aircraft, has a shape similar to an end portion of an ellipse. The outer edge of the body decreases in lateral width gently, and the rear end is rounded back to the mounting surface.
The housing or body surface along the maximum outward dimension provides a location on which a static sensing port or ports can be placed.
The body extends from the mounting surface only a small amount and can remain in the boundary layer air along the aircraft surface. The body or housing is exposed to airflow and is positioned to provide a useable differential in pressure signals between the angle sensing ports.
In addition, the body of the semi-flush sensor has a port facing upstream, at its forward end, to provide a local total pressure or pitot pressure signal.
The mounting plate for the sensor can be flush with the aircraft skin, and can be curved to blend with curved aircraft surfaces. The xe2x80x9cbubblexe2x80x9d or housing forming the sensor body protrudes slightly into the airsteam, at a level and location to avoid adverse effects of aircraft components, and creates a small local disturbance in the airflow. The pressure ports can be located at various locations to measure the desired air data parameters. The housing forming the sensor body can be molded or formed integrally with the aircraft skin of a composite material or metal fuselage.
The protrusion from the aircraft skin is in the range of a few centimeters, and thus the sensor is lighter and has less drag than existing strut mounted air data sensing probes. The smaller size means that less power is required to deice or anti-ice. Very little ice accumulates near or on the aircraft fuselage skin, whereas strut mounted probes and vanes operate in a region spaced from the aircraft skin where moisture is concentrated due to the effects of flow past the fuselage of an aircraft. There are no moving parts in the present device, and the small size and aerodynamic shape means lower drag, lower weight, lower radar cross section, and less susceptibility to damage, such as bird strikes, refueling booms, and bumping by maintenance personnel. Many things that damage a strut mounted probe will merely flow over the aerodynamic shape of the present sensor. Since the sensor body does not protrude as far into the airstream from the fuselage or aircraft skin surface, there are fewer items that are likely to strike the protuberance or semi-flush sensor.